The present invention relates to an operating method for a cooling section for a flat rolling stock, wherein the flat rolling stock is guided through a working region of a number of spray beams, a liquid coolant is fed to the spray beams from a reservoir via a pump and a supply line system, and opening positions of valves arranged upstream of the spray beams within the supply line system are set according to a respective partial flow to be applied to the flat rolling stock by means of the respective spray beam.
The present invention further relates to a control device for a cooling section for a flat rolling stock, wherein the control device sets valves, which are arranged in a supply line system that extends between a reservoir for a liquid coolant and a number of spray beams, according to a respective partial flow to be applied to the flat rolling stock by means of the respective spray beam.
The present invention further relates to a computer program which comprises machine code that can be directly executed by a software-programmable control device, wherein the execution of the machine code by the software-programmable control device has the effect of accordingly forming the control device.
The present invention further relates to a cooling section for a flat rolling stock, wherein the cooling section has a working region through which the flat rolling stock is guided, the working region can be supplied with a liquid coolant by means of a number of spray beams, the liquid coolant is fed to the spray beams from a reservoir for the liquid coolant via a pump and a supply line system, valves are arranged upstream of the spray beams within the supply line system, the cooling section has a control device, and opening positions of the valves are set by the control device according to a respective partial flow to be applied to the flat rolling stock by means of the respective spray beam.
The abovementioned subject matter is generally known.
DE 198 54 675 A1 discloses an operating method for a cooling section for a flat rolling stock, wherein the flat rolling stock is guided through a working region of a number of spray beams. A liquid coolant is fed to the spray beams from a reservoir via a pump and a supply line system.
U.S. Pat. No. 3,423,254 A discloses an operating method for a cooling section for a flat rolling stock, wherein the flat rolling stock is guided through a working region of a number of spray beams. A liquid coolant is fed to the spray beams from a reservoir via a pump and a supply line system.
U.S. Pat. No. 4,720,310 A discloses an operating method for a cooling section for a flat rolling stock, wherein the flat rolling stock is guided through a working region of a number of spray beams. A liquid coolant is fed to the upper and lower rollers from a reservoir via a respective pump and a supply line system. Valves are not present in the supply line system. A respective delivery power of the respective pump is set.
The prior art often involves what is termed laminar cooling. In laminar cooling, the cooling section has a number of spray beams which apply the liquid coolant, either only from above or both from above and from below, onto the flat rolling stock.
More recently, what is termed power cooling is also known. Power cooling, that is, the intensive cooling of hot rolling material is a novel cooling method for cooling a rolling material during or immediately after hot rolling. It serves to set, in a targeted manner, the microstructure and thus the mechanical properties of the end product. In particular, what are termed AHSS (advanced high strength steels) require ever more cooling intensity and cooling flexibility. These requirements are satisfied with power cooling. In power cooling, the spray beams apply markedly greater volume flow rates of liquid coolant to the flat rolling stock than is the case in laminar cooling.
If laminar cooling is to be brought about using a cooling section which is configured for power cooling, it is not sufficient to merely fully open and close the valves arranged upstream of the spray beams. The consequence of this would be that the large quantity of liquid coolant which is required for power cooling is applied to the flat rolling stock. It is therefore necessary to apply, by means of the respective spray beam, a substantially smaller quantity of liquid coolant to the flat rolling stock.
In the prior art, it is known to provide two separate supply line systems, each assigned its own pump. If power cooling is to be carried out, liquid coolant is supplied to the spray beams via one supply line system. If laminar cooling is to be carried out, liquid coolant is supplied to the spray beams via the other supply line system. It is alternatively possible for each of the spray beams to have its own respective valve and for the supply line systems to be unified only downstream of the respective valves. Alternatively, the supply line systems can be unified upstream of the respective valve. In this latter case, the supply line systems are locked with respect to one another, for example by means of check valves.
It would be desirable to be able to supply the spray beams with the liquid coolant via a single supply line system. However, in practice, there is a problem that power cooling requires a relatively high line pressure and that the liquid coolant flowing through the respective valve cavitates if the partial flow of liquid coolant flowing through the respective valve is set to a low value, as is necessary for laminar cooling.